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Allows Rails to manage a second database in your projects (gets you to secondbase)
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Gemfile SecondBase head now only supports Rails 3.x! Aug 31, 2012
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VERSION SecondBase head now only supports Rails 3.x! Aug 31, 2012



SecondBase adds a second database to your application. While Rails enables you to establish connections to as many external databases as you like, Rails can only manage a single database with it's migration and testing tasks.

SecondBase enables Rails to work with, and manage, a second database (almost) transparently. As a developer, you should not even realize a second database is in play. Core rake tasks such as rake db:create, rake db:migrate, and rake test will continue to work seamlessly with both databases without you, the developer, having to run any extra rake tasks.

SecondBase works with Rails 2.3.x and 3.0.x. I've not tried to use SecondBase with Rails 3.1 yet, although someone has submitted a pull request fixing a 3.1 issue, so I assume it's working OK?

Contributing to SecondBase

  • Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet

  • Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it

  • Fork the project

  • Start a feature/bugfix branch

  • Commit and push until you are happy with your contribution

  • Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.

  • Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

System Requirements

SecondBase now supports Rails 2.x and Rails 3.x.


Modify your Gemfile to include SecondBase:

gem 'secondbase', '0.5.0'

Run `bundle install`. You thought it would be harder? If you're using Rails 2.x, then yes, a little bit harder. You must also add this to your Rakefile:

require 'secondbase/tasks' if defined?(SecondBase)

PLEASE NOTE that if you are using bundler with Rails 2.x, then you simply need to add this to your Rakefile:

require 'secondbase/tasks'



Configure your database.yml to define your SecondBase:

# Your normal rails definitions...
  adapter: mysql  #postgres, oracle, etc
  encoding: utf8
  database: development

  adapter: mysql  #postgres, oracle, etc
  encoding: utf8
  database: test

# Your secondbase database configurations...
    adapter: mysql
    encoding: utf8
    database: secondbase_development

    adapter: mysql
    encoding: utf8
    database: secondbase_test


SecondBase comes with a generator to assist in managing your migrations

Rails 3.x:

rails generator secondbase:migration CreateWidgetsTable

Rails 2.x:

script/generate secondbase_migration CreateWidgetsTable

The generator will organize your second (data)base migrations alongside of your primary database. The above command will generate the file:


To run your migrations, simply run:

rake db:migrate

This will migrate your first and second (data)bases. If, for some reason, you only want to migrate your second (data)base, run:

rake db:migrate:secondbase

Please note that migrating up and migrating down must be done specifically on your first or second (data)base. As usual, to migrate your first (data)base up or down to version 20101203211338, you could run:

rake db:migrate:up VERSION=20101005311335
rake db:migrate:down VERSION=20101005311335

To migrate your second (data)base up or down to version 20101203211338, you would run:

rake db:migrate:up:secondbase VERSION=20101203211338
rake db:migrate:down:secondbase VERSION=20101203211338


Every model in your project that extends ActiveRecord::Base will point to the database defined by Rails.env. This is the default Rails behavior and should be of no surprise to you. So how do we point our models to the second (data)base?

SecondBase offers a base model that you can simply extend:

require 'secondbase/model'

class Widget < SecondBase::Base
  # you're Widget model is now pointing to your second (data)base table 'widgets'

ActiveRecord associations will still work between your Firstbase and SecondBase models!

# Notice how normal this all looks...
class User < ActiveRecord::Base
  has_many :widgets

Rake Tasks & Custom Classes

If you need to write rake tasks, or some other code that does not extend ActiveRecord, you can simply establish a connection to your second (data)base:


Please note that this is equivalent to using ActiveRecord::Base.establish_connection(config) and will reset the base connection of your ENTIRE application. No worries, to move the runner back to first you can use:



Tests can still be run using `rake test` or `rake test:units`, etc. However, if you are using fixtures, you will need to update your TestHelper class to include:

require 'secondbase/fixtures'

This is patch to fixtures that will identify the fixtures which belong to models that extend SecondBase::Base. The patch will then ensure that the table descendants of SecondBase::Base get loaded into your second test (data)base.

At this time, I can verify that SecondBase works with Fixtures, Machinist and FactoryGirl. Conceivably, other test factories should work, but there is currently no support for this. If you have the time to update this gem to be test object compatible, by all means…


  • Migration generator in Rails 3.x needs support for attribute generation (similar to rails generate migration). For example: `rails generate secondbase:migration AddTitleBodyToPost title:string body:text published:boolean`

  • rake db:fixtures:load is currently broken. Like many other things I have fixed, it assumes you only one a single database and attempts to load all fixtures into it. I don't believe we can get away with alias chaining this one, I think (like the Fixtures class), we'll have to freedom patch it.

  • TESTS!! Not 100% sure how to test the rake tasks, but I can definitely write tests for the classes and generators. I did this in my spare time, sorry…


Copyright © 2010 karledurante. See LICENSE.txt for further details.

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